친구분?
II know 친구 means friend.
What does the 분 mean?

Question

Answer

1. 분 means "person" in honorific expression.
ex)
여기 그런 분 안 계세요 
There is no such person here. 
손님 자리는 저 신사 분 옆입니다 
Your seat is next to that gentleman.
다시 가족 분들이 미국으로 돌아가신 줄로 알았습니다. 
I figured your family moved back to the States.

친구 분 is honorific expression of 친구
팬 분 is honorific expression of 팬(fan)
팬 분들 is honorific expression of 팬들(fans)

2. 분 is honorific form of 명 used for counting people.
ex)
The history department has five lecturers and one professor.
역사학과에는 강사 다섯 분과 교수 한 분이 있다. 
Table for five?
다섯 분이신가요?

Answer

분 is an honorific form of person.
분 is also usually added before words and makes them sound polite.

I suppose 친구분? is short for "저 분이 당신의 친구 분이세요?" which means "Is that your friend?"

As for the informal version, it would be: 저 사람이 너의 친구야?

Answer

the way i know it is you use 분 when you are referring to a group of people

for example 여러분 is everyone along with 모든분

also maybe a word you recognize is 팬분 "fans"